root/drivers/bus/moxtet.c
// SPDX-License-Identifier: GPL-2.0
/*
 * Turris Mox module configuration bus driver
 *
 * Copyright (C) 2019 Marek BehĂșn <kabel@kernel.org>
 */

#include <dt-bindings/bus/moxtet.h>
#include <linux/bitops.h>
#include <linux/debugfs.h>
#include <linux/hex.h>
#include <linux/interrupt.h>
#include <linux/module.h>
#include <linux/moxtet.h>
#include <linux/mutex.h>
#include <linux/of_device.h>
#include <linux/of_irq.h>
#include <linux/spi/spi.h>

/*
 * @name:       module name for sysfs
 * @hwirq_base: base index for IRQ for this module (-1 if no IRQs)
 * @nirqs:      how many interrupts does the shift register provide
 * @desc:       module description for kernel log
 */
static const struct {
        const char *name;
        int hwirq_base;
        int nirqs;
        const char *desc;
} mox_module_table[] = {
        /* do not change order of this array! */
        { NULL,          0,                     0, NULL },
        { "sfp",        -1,                     0, "MOX D (SFP cage)" },
        { "pci",        MOXTET_IRQ_PCI,         1, "MOX B (Mini-PCIe)" },
        { "topaz",      MOXTET_IRQ_TOPAZ,       1, "MOX C (4 port switch)" },
        { "peridot",    MOXTET_IRQ_PERIDOT(0),  1, "MOX E (8 port switch)" },
        { "usb3",       MOXTET_IRQ_USB3,        2, "MOX F (USB 3.0)" },
        { "pci-bridge", -1,                     0, "MOX G (Mini-PCIe bridge)" },
};

static inline bool mox_module_known(unsigned int id)
{
        return id >= TURRIS_MOX_MODULE_FIRST && id <= TURRIS_MOX_MODULE_LAST;
}

static inline const char *mox_module_name(unsigned int id)
{
        if (mox_module_known(id))
                return mox_module_table[id].name;
        else
                return "unknown";
}

#define DEF_MODULE_ATTR(name, fmt, ...)                                 \
static ssize_t                                                          \
module_##name##_show(struct device *dev, struct device_attribute *a,    \
                     char *buf)                                         \
{                                                                       \
        struct moxtet_device *mdev = to_moxtet_device(dev);             \
        return sprintf(buf, (fmt), __VA_ARGS__);                        \
}                                                                       \
static DEVICE_ATTR_RO(module_##name)

DEF_MODULE_ATTR(id, "0x%x\n", mdev->id);
DEF_MODULE_ATTR(name, "%s\n", mox_module_name(mdev->id));
DEF_MODULE_ATTR(description, "%s\n",
                mox_module_known(mdev->id) ? mox_module_table[mdev->id].desc
                                           : "");

static struct attribute *moxtet_dev_attrs[] = {
        &dev_attr_module_id.attr,
        &dev_attr_module_name.attr,
        &dev_attr_module_description.attr,
        NULL,
};

static const struct attribute_group moxtet_dev_group = {
        .attrs = moxtet_dev_attrs,
};

static const struct attribute_group *moxtet_dev_groups[] = {
        &moxtet_dev_group,
        NULL,
};

static int moxtet_match(struct device *dev, const struct device_driver *drv)
{
        struct moxtet_device *mdev = to_moxtet_device(dev);
        const struct moxtet_driver *tdrv = to_moxtet_driver(drv);
        const enum turris_mox_module_id *t;

        if (of_driver_match_device(dev, drv))
                return 1;

        if (!tdrv->id_table)
                return 0;

        for (t = tdrv->id_table; *t; ++t)
                if (*t == mdev->id)
                        return 1;

        return 0;
}

static const struct bus_type moxtet_bus_type = {
        .name           = "moxtet",
        .dev_groups     = moxtet_dev_groups,
        .match          = moxtet_match,
};

int __moxtet_register_driver(struct module *owner,
                             struct moxtet_driver *mdrv)
{
        mdrv->driver.owner = owner;
        mdrv->driver.bus = &moxtet_bus_type;
        return driver_register(&mdrv->driver);
}
EXPORT_SYMBOL_GPL(__moxtet_register_driver);

static int moxtet_dev_check(struct device *dev, void *data)
{
        struct moxtet_device *mdev = to_moxtet_device(dev);
        struct moxtet_device *new_dev = data;

        if (mdev->moxtet == new_dev->moxtet && mdev->id == new_dev->id &&
            mdev->idx == new_dev->idx)
                return -EBUSY;
        return 0;
}

static void moxtet_dev_release(struct device *dev)
{
        struct moxtet_device *mdev = to_moxtet_device(dev);

        put_device(mdev->moxtet->dev);
        kfree(mdev);
}

static struct moxtet_device *
moxtet_alloc_device(struct moxtet *moxtet)
{
        struct moxtet_device *dev;

        if (!get_device(moxtet->dev))
                return NULL;

        dev = kzalloc_obj(*dev);
        if (!dev) {
                put_device(moxtet->dev);
                return NULL;
        }

        dev->moxtet = moxtet;
        dev->dev.parent = moxtet->dev;
        dev->dev.bus = &moxtet_bus_type;
        dev->dev.release = moxtet_dev_release;

        device_initialize(&dev->dev);

        return dev;
}

static int moxtet_add_device(struct moxtet_device *dev)
{
        static DEFINE_MUTEX(add_mutex);
        int ret;

        if (dev->idx >= TURRIS_MOX_MAX_MODULES || dev->id > 0xf)
                return -EINVAL;

        dev_set_name(&dev->dev, "moxtet-%s.%u", mox_module_name(dev->id),
                     dev->idx);

        mutex_lock(&add_mutex);

        ret = bus_for_each_dev(&moxtet_bus_type, NULL, dev,
                               moxtet_dev_check);
        if (ret)
                goto done;

        ret = device_add(&dev->dev);
        if (ret < 0)
                dev_err(dev->moxtet->dev, "can't add %s, status %d\n",
                        dev_name(dev->moxtet->dev), ret);

done:
        mutex_unlock(&add_mutex);
        return ret;
}

static int __unregister(struct device *dev, void *null)
{
        if (dev->of_node) {
                of_node_clear_flag(dev->of_node, OF_POPULATED);
                of_node_put(dev->of_node);
        }

        device_unregister(dev);

        return 0;
}

static struct moxtet_device *
of_register_moxtet_device(struct moxtet *moxtet, struct device_node *nc)
{
        struct moxtet_device *dev;
        u32 val;
        int ret;

        dev = moxtet_alloc_device(moxtet);
        if (!dev) {
                dev_err(moxtet->dev,
                        "Moxtet device alloc error for %pOF\n", nc);
                return ERR_PTR(-ENOMEM);
        }

        ret = of_property_read_u32(nc, "reg", &val);
        if (ret) {
                dev_err(moxtet->dev, "%pOF has no valid 'reg' property (%d)\n",
                        nc, ret);
                goto err_put;
        }

        dev->idx = val;

        if (dev->idx >= TURRIS_MOX_MAX_MODULES) {
                dev_err(moxtet->dev, "%pOF Moxtet address 0x%x out of range\n",
                        nc, dev->idx);
                ret = -EINVAL;
                goto err_put;
        }

        dev->id = moxtet->modules[dev->idx];

        if (!dev->id) {
                dev_err(moxtet->dev, "%pOF Moxtet address 0x%x is empty\n", nc,
                        dev->idx);
                ret = -ENODEV;
                goto err_put;
        }

        of_node_get(nc);
        dev->dev.of_node = nc;

        ret = moxtet_add_device(dev);
        if (ret) {
                dev_err(moxtet->dev,
                        "Moxtet device register error for %pOF\n", nc);
                of_node_put(nc);
                goto err_put;
        }

        return dev;

err_put:
        put_device(&dev->dev);
        return ERR_PTR(ret);
}

static void of_register_moxtet_devices(struct moxtet *moxtet)
{
        struct moxtet_device *dev;
        struct device_node *nc;

        if (!moxtet->dev->of_node)
                return;

        for_each_available_child_of_node(moxtet->dev->of_node, nc) {
                if (of_node_test_and_set_flag(nc, OF_POPULATED))
                        continue;
                dev = of_register_moxtet_device(moxtet, nc);
                if (IS_ERR(dev)) {
                        dev_warn(moxtet->dev,
                                 "Failed to create Moxtet device for %pOF\n",
                                 nc);
                        of_node_clear_flag(nc, OF_POPULATED);
                }
        }
}

static void
moxtet_register_devices_from_topology(struct moxtet *moxtet)
{
        struct moxtet_device *dev;
        int i, ret;

        for (i = 0; i < moxtet->count; ++i) {
                dev = moxtet_alloc_device(moxtet);
                if (!dev) {
                        dev_err(moxtet->dev, "Moxtet device %u alloc error\n",
                                i);
                        continue;
                }

                dev->idx = i;
                dev->id = moxtet->modules[i];

                ret = moxtet_add_device(dev);
                if (ret && ret != -EBUSY) {
                        put_device(&dev->dev);
                        dev_err(moxtet->dev,
                                "Moxtet device %u register error: %i\n", i,
                                ret);
                }
        }
}

/*
 * @nsame:      how many modules with same id are already in moxtet->modules
 */
static int moxtet_set_irq(struct moxtet *moxtet, int idx, int id, int nsame)
{
        int i, first;
        struct moxtet_irqpos *pos;

        first = mox_module_table[id].hwirq_base +
                nsame * mox_module_table[id].nirqs;

        if (first + mox_module_table[id].nirqs > MOXTET_NIRQS)
                return -EINVAL;

        for (i = 0; i < mox_module_table[id].nirqs; ++i) {
                pos = &moxtet->irq.position[first + i];
                pos->idx = idx;
                pos->bit = i;
                moxtet->irq.exists |= BIT(first + i);
        }

        return 0;
}

static int moxtet_find_topology(struct moxtet *moxtet)
{
        u8 buf[TURRIS_MOX_MAX_MODULES];
        int cnts[TURRIS_MOX_MODULE_LAST];
        int i, ret;

        memset(cnts, 0, sizeof(cnts));

        ret = spi_read(to_spi_device(moxtet->dev), buf, TURRIS_MOX_MAX_MODULES);
        if (ret < 0)
                return ret;

        if (buf[0] == TURRIS_MOX_CPU_ID_EMMC) {
                dev_info(moxtet->dev, "Found MOX A (eMMC CPU) module\n");
        } else if (buf[0] == TURRIS_MOX_CPU_ID_SD) {
                dev_info(moxtet->dev, "Found MOX A (CPU) module\n");
        } else {
                dev_err(moxtet->dev, "Invalid Turris MOX A CPU module 0x%02x\n",
                        buf[0]);
                return -ENODEV;
        }

        moxtet->count = 0;

        for (i = 1; i < TURRIS_MOX_MAX_MODULES; ++i) {
                int id;

                if (buf[i] == 0xff)
                        break;

                id = buf[i] & 0xf;

                moxtet->modules[i-1] = id;
                ++moxtet->count;

                if (mox_module_known(id)) {
                        dev_info(moxtet->dev, "Found %s module\n",
                                 mox_module_table[id].desc);

                        if (moxtet_set_irq(moxtet, i-1, id, cnts[id]++) < 0)
                                dev_err(moxtet->dev,
                                        "  Cannot set IRQ for module %s\n",
                                        mox_module_table[id].desc);
                } else {
                        dev_warn(moxtet->dev,
                                 "Unknown Moxtet module found (ID 0x%02x)\n",
                                 id);
                }
        }

        return 0;
}

static int moxtet_spi_read(struct moxtet *moxtet, u8 *buf)
{
        struct spi_transfer xfer = {
                .rx_buf = buf,
                .tx_buf = moxtet->tx,
                .len = moxtet->count + 1
        };
        int ret;

        mutex_lock(&moxtet->lock);

        ret = spi_sync_transfer(to_spi_device(moxtet->dev), &xfer, 1);

        mutex_unlock(&moxtet->lock);

        return ret;
}

int moxtet_device_read(struct device *dev)
{
        struct moxtet_device *mdev = to_moxtet_device(dev);
        struct moxtet *moxtet = mdev->moxtet;
        u8 buf[TURRIS_MOX_MAX_MODULES];
        int ret;

        if (mdev->idx >= moxtet->count)
                return -EINVAL;

        ret = moxtet_spi_read(moxtet, buf);
        if (ret < 0)
                return ret;

        return buf[mdev->idx + 1] >> 4;
}
EXPORT_SYMBOL_GPL(moxtet_device_read);

int moxtet_device_write(struct device *dev, u8 val)
{
        struct moxtet_device *mdev = to_moxtet_device(dev);
        struct moxtet *moxtet = mdev->moxtet;
        int ret;

        if (mdev->idx >= moxtet->count)
                return -EINVAL;

        mutex_lock(&moxtet->lock);

        moxtet->tx[moxtet->count - mdev->idx] = val;

        ret = spi_write(to_spi_device(moxtet->dev), moxtet->tx,
                        moxtet->count + 1);

        mutex_unlock(&moxtet->lock);

        return ret;
}
EXPORT_SYMBOL_GPL(moxtet_device_write);

int moxtet_device_written(struct device *dev)
{
        struct moxtet_device *mdev = to_moxtet_device(dev);
        struct moxtet *moxtet = mdev->moxtet;

        if (mdev->idx >= moxtet->count)
                return -EINVAL;

        return moxtet->tx[moxtet->count - mdev->idx];
}
EXPORT_SYMBOL_GPL(moxtet_device_written);

#ifdef CONFIG_DEBUG_FS
static int moxtet_debug_open(struct inode *inode, struct file *file)
{
        file->private_data = inode->i_private;

        return nonseekable_open(inode, file);
}

static ssize_t input_read(struct file *file, char __user *buf, size_t len,
                          loff_t *ppos)
{
        struct moxtet *moxtet = file->private_data;
        u8 bin[TURRIS_MOX_MAX_MODULES];
        u8 hex[sizeof(bin) * 2 + 1];
        int ret, n;

        ret = moxtet_spi_read(moxtet, bin);
        if (ret < 0)
                return ret;

        n = moxtet->count + 1;
        bin2hex(hex, bin, n);

        hex[2*n] = '\n';

        return simple_read_from_buffer(buf, len, ppos, hex, 2*n + 1);
}

static const struct file_operations input_fops = {
        .owner  = THIS_MODULE,
        .open   = moxtet_debug_open,
        .read   = input_read,
};

static ssize_t output_read(struct file *file, char __user *buf, size_t len,
                           loff_t *ppos)
{
        struct moxtet *moxtet = file->private_data;
        u8 hex[TURRIS_MOX_MAX_MODULES * 2 + 1];
        u8 *p = hex;
        int i;

        mutex_lock(&moxtet->lock);

        for (i = 0; i < moxtet->count; ++i)
                p = hex_byte_pack(p, moxtet->tx[moxtet->count - i]);

        mutex_unlock(&moxtet->lock);

        *p++ = '\n';

        return simple_read_from_buffer(buf, len, ppos, hex, p - hex);
}

static ssize_t output_write(struct file *file, const char __user *buf,
                            size_t len, loff_t *ppos)
{
        struct moxtet *moxtet = file->private_data;
        u8 bin[TURRIS_MOX_MAX_MODULES];
        u8 hex[sizeof(bin) * 2 + 1];
        ssize_t res;
        loff_t dummy = 0;
        int err, i;

        if (len > 2 * moxtet->count + 1 || len < 2 * moxtet->count)
                return -EINVAL;

        res = simple_write_to_buffer(hex, sizeof(hex), &dummy, buf, len);
        if (res < 0)
                return res;

        if (len % 2 == 1 && hex[len - 1] != '\n')
                return -EINVAL;

        err = hex2bin(bin, hex, moxtet->count);
        if (err < 0)
                return -EINVAL;

        mutex_lock(&moxtet->lock);

        for (i = 0; i < moxtet->count; ++i)
                moxtet->tx[moxtet->count - i] = bin[i];

        err = spi_write(to_spi_device(moxtet->dev), moxtet->tx,
                        moxtet->count + 1);

        mutex_unlock(&moxtet->lock);

        return err < 0 ? err : len;
}

static const struct file_operations output_fops = {
        .owner  = THIS_MODULE,
        .open   = moxtet_debug_open,
        .read   = output_read,
        .write  = output_write,
};

static int moxtet_register_debugfs(struct moxtet *moxtet)
{
        struct dentry *root, *entry;

        root = debugfs_create_dir("moxtet", NULL);

        if (IS_ERR(root))
                return PTR_ERR(root);

        entry = debugfs_create_file_unsafe("input", 0444, root, moxtet,
                                           &input_fops);
        if (IS_ERR(entry))
                goto err_remove;

        entry = debugfs_create_file_unsafe("output", 0644, root, moxtet,
                                           &output_fops);
        if (IS_ERR(entry))
                goto err_remove;

        moxtet->debugfs_root = root;

        return 0;
err_remove:
        debugfs_remove_recursive(root);
        return PTR_ERR(entry);
}

static void moxtet_unregister_debugfs(struct moxtet *moxtet)
{
        debugfs_remove_recursive(moxtet->debugfs_root);
}
#else
static inline int moxtet_register_debugfs(struct moxtet *moxtet)
{
        return 0;
}

static inline void moxtet_unregister_debugfs(struct moxtet *moxtet)
{
}
#endif

static int moxtet_irq_domain_map(struct irq_domain *d, unsigned int irq,
                                 irq_hw_number_t hw)
{
        struct moxtet *moxtet = d->host_data;

        if (hw >= MOXTET_NIRQS || !(moxtet->irq.exists & BIT(hw))) {
                dev_err(moxtet->dev, "Invalid hw irq number\n");
                return -EINVAL;
        }

        irq_set_chip_data(irq, d->host_data);
        irq_set_chip_and_handler(irq, &moxtet->irq.chip, handle_level_irq);

        return 0;
}

static int moxtet_irq_domain_xlate(struct irq_domain *d,
                                   struct device_node *ctrlr,
                                   const u32 *intspec, unsigned int intsize,
                                   unsigned long *out_hwirq,
                                   unsigned int *out_type)
{
        struct moxtet *moxtet = d->host_data;
        int irq;

        if (WARN_ON(intsize < 1))
                return -EINVAL;

        irq = intspec[0];

        if (irq >= MOXTET_NIRQS || !(moxtet->irq.exists & BIT(irq)))
                return -EINVAL;

        *out_hwirq = irq;
        *out_type = IRQ_TYPE_NONE;
        return 0;
}

static const struct irq_domain_ops moxtet_irq_domain = {
        .map = moxtet_irq_domain_map,
        .xlate = moxtet_irq_domain_xlate,
};

static void moxtet_irq_mask(struct irq_data *d)
{
        struct moxtet *moxtet = irq_data_get_irq_chip_data(d);

        moxtet->irq.masked |= BIT(d->hwirq);
}

static void moxtet_irq_unmask(struct irq_data *d)
{
        struct moxtet *moxtet = irq_data_get_irq_chip_data(d);

        moxtet->irq.masked &= ~BIT(d->hwirq);
}

static void moxtet_irq_print_chip(struct irq_data *d, struct seq_file *p)
{
        struct moxtet *moxtet = irq_data_get_irq_chip_data(d);
        struct moxtet_irqpos *pos = &moxtet->irq.position[d->hwirq];
        int id;

        id = moxtet->modules[pos->idx];

        seq_printf(p, "moxtet-%s.%i#%i", mox_module_name(id), pos->idx,
                   pos->bit);
}

static const struct irq_chip moxtet_irq_chip = {
        .name                   = "moxtet",
        .irq_mask               = moxtet_irq_mask,
        .irq_unmask             = moxtet_irq_unmask,
        .irq_print_chip         = moxtet_irq_print_chip,
};

static int moxtet_irq_read(struct moxtet *moxtet, unsigned long *map)
{
        struct moxtet_irqpos *pos = moxtet->irq.position;
        u8 buf[TURRIS_MOX_MAX_MODULES];
        int i, ret;

        ret = moxtet_spi_read(moxtet, buf);
        if (ret < 0)
                return ret;

        *map = 0;

        for_each_set_bit(i, &moxtet->irq.exists, MOXTET_NIRQS) {
                if (!(buf[pos[i].idx + 1] & BIT(4 + pos[i].bit)))
                        set_bit(i, map);
        }

        return 0;
}

static irqreturn_t moxtet_irq_thread_fn(int irq, void *data)
{
        struct moxtet *moxtet = data;
        unsigned long set;
        int nhandled = 0, i, sub_irq, ret;

        ret = moxtet_irq_read(moxtet, &set);
        if (ret < 0)
                goto out;

        set &= ~moxtet->irq.masked;

        do {
                for_each_set_bit(i, &set, MOXTET_NIRQS) {
                        sub_irq = irq_find_mapping(moxtet->irq.domain, i);
                        handle_nested_irq(sub_irq);
                        dev_dbg(moxtet->dev, "%i irq\n", i);
                        ++nhandled;
                }

                ret = moxtet_irq_read(moxtet, &set);
                if (ret < 0)
                        goto out;

                set &= ~moxtet->irq.masked;
        } while (set);

out:
        return (nhandled > 0 ? IRQ_HANDLED : IRQ_NONE);
}

static void moxtet_irq_free(struct moxtet *moxtet)
{
        int i, irq;

        for (i = 0; i < MOXTET_NIRQS; ++i) {
                if (moxtet->irq.exists & BIT(i)) {
                        irq = irq_find_mapping(moxtet->irq.domain, i);
                        irq_dispose_mapping(irq);
                }
        }

        irq_domain_remove(moxtet->irq.domain);
}

static int moxtet_irq_setup(struct moxtet *moxtet)
{
        int i, ret;

        moxtet->irq.domain = irq_domain_create_simple(dev_fwnode(moxtet->dev), MOXTET_NIRQS, 0,
                                                      &moxtet_irq_domain, moxtet);
        if (moxtet->irq.domain == NULL) {
                dev_err(moxtet->dev, "Could not add IRQ domain\n");
                return -ENOMEM;
        }

        for (i = 0; i < MOXTET_NIRQS; ++i)
                if (moxtet->irq.exists & BIT(i))
                        irq_create_mapping(moxtet->irq.domain, i);

        moxtet->irq.chip = moxtet_irq_chip;
        moxtet->irq.masked = ~0;

        ret = request_threaded_irq(moxtet->dev_irq, NULL, moxtet_irq_thread_fn,
                                   IRQF_SHARED | IRQF_ONESHOT, "moxtet", moxtet);
        if (ret < 0)
                goto err_free;

        return 0;

err_free:
        moxtet_irq_free(moxtet);
        return ret;
}

static int moxtet_probe(struct spi_device *spi)
{
        struct moxtet *moxtet;
        int ret;

        ret = spi_setup(spi);
        if (ret < 0)
                return ret;

        moxtet = devm_kzalloc(&spi->dev, sizeof(struct moxtet),
                              GFP_KERNEL);
        if (!moxtet)
                return -ENOMEM;

        moxtet->dev = &spi->dev;
        spi_set_drvdata(spi, moxtet);

        mutex_init(&moxtet->lock);

        moxtet->dev_irq = of_irq_get(moxtet->dev->of_node, 0);
        if (moxtet->dev_irq == -EPROBE_DEFER)
                return -EPROBE_DEFER;

        if (moxtet->dev_irq <= 0) {
                dev_err(moxtet->dev, "No IRQ resource found\n");
                return -ENXIO;
        }

        ret = moxtet_find_topology(moxtet);
        if (ret < 0)
                return ret;

        if (moxtet->irq.exists) {
                ret = moxtet_irq_setup(moxtet);
                if (ret < 0)
                        return ret;
        }

        of_register_moxtet_devices(moxtet);
        moxtet_register_devices_from_topology(moxtet);

        ret = moxtet_register_debugfs(moxtet);
        if (ret < 0)
                dev_warn(moxtet->dev, "Failed creating debugfs entries: %i\n",
                         ret);

        return 0;
}

static void moxtet_remove(struct spi_device *spi)
{
        struct moxtet *moxtet = spi_get_drvdata(spi);

        free_irq(moxtet->dev_irq, moxtet);

        moxtet_irq_free(moxtet);

        moxtet_unregister_debugfs(moxtet);

        device_for_each_child(moxtet->dev, NULL, __unregister);

        mutex_destroy(&moxtet->lock);
}

static const struct spi_device_id moxtet_spi_ids[] = {
        { "moxtet" },
        { },
};
MODULE_DEVICE_TABLE(spi, moxtet_spi_ids);

static const struct of_device_id moxtet_dt_ids[] = {
        { .compatible = "cznic,moxtet" },
        {},
};
MODULE_DEVICE_TABLE(of, moxtet_dt_ids);

static struct spi_driver moxtet_spi_driver = {
        .driver = {
                .name           = "moxtet",
                .of_match_table = moxtet_dt_ids,
        },
        .id_table       = moxtet_spi_ids,
        .probe          = moxtet_probe,
        .remove         = moxtet_remove,
};

static int __init moxtet_init(void)
{
        int ret;

        ret = bus_register(&moxtet_bus_type);
        if (ret < 0) {
                pr_err("moxtet bus registration failed: %d\n", ret);
                goto error;
        }

        ret = spi_register_driver(&moxtet_spi_driver);
        if (ret < 0) {
                pr_err("moxtet spi driver registration failed: %d\n", ret);
                goto error_bus;
        }

        return 0;

error_bus:
        bus_unregister(&moxtet_bus_type);
error:
        return ret;
}
postcore_initcall_sync(moxtet_init);

static void __exit moxtet_exit(void)
{
        spi_unregister_driver(&moxtet_spi_driver);
        bus_unregister(&moxtet_bus_type);
}
module_exit(moxtet_exit);

MODULE_AUTHOR("Marek Behun <kabel@kernel.org>");
MODULE_DESCRIPTION("CZ.NIC's Turris Mox module configuration bus");
MODULE_LICENSE("GPL v2");